Upon learning of a large gathering, ascertain how the event is being advertised. Is it advertised in the local student paper or is it being promoted through digital media, including Websites, Facebook, Twitter, etc.? Use your knowledge of how the event is being promoted to calculate how many people are aware of it.
Next, determine who will be attending. Are you expecting current students, returning alumni, or attendees who are not members of the university community? Is this event likely to draw a "counter-group?"
Once you've given thought to how many people and from what groups people will attend, it's time to consider riot scenarios. If there is a riot, will the rioters likely target each other? Rival fans? Property? Folks with badges like you?
Knowing the terrain will also help you prevent riots. Brainstorm with members of the student body, university officials, and members of the community to assess what could be a flashpoint location.
In some stadiums all the inexpensive student seats are accessed through one gate. That means that most of the students will be exiting the game through that gate, and it can be a flashpoint. You also have to consider flashpoints away from the stadium. A good bet is an entertainment area such as a strip of bars where many of the spectators go after the game.